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Evaluation of the Neurologic Patient
Patients with neurologic symptoms are approached in a stepwise manner termed the neurologic method, which consists of the following:
Identifying the anatomy and pathophysiology of the lesion through careful history taking and an accurate neurologic examination markedly narrows the differential diagnosis and thus the number of tests needed. This approach should not be replaced by reflex ordering of CT, MRI, and other laboratory testing; doing so leads to error and unnecessary cost.
To identify the anatomic location, the examiner considers questions such as
Specific parts of the nervous system to be considered include the cerebral cortex, subcortical white matter, basal ganglia, thalamus, cerebellum, brain stem, spinal cord, brachial or pelvic plexus, peripheral nerves, neuromuscular junction, and muscle.
Once the location of the lesion is identified, categories of pathophysiologic causes are considered; they include
When appropriately applied, the neurologic method provides an orderly approach to even the most complex case, and clinicians are far less likely to be fooled by neurologic mimicry—eg, when symptoms of an acute stroke are actually due to a brain tumor or when rapidly ascending paralysis suggesting Guillain-Barré syndrome is actually due to spinal cord compression.
The history is the most important part of the neurologic evaluation. Patients should be put at ease and allowed to tell their story in their own words. Usually, a clinician can quickly determine whether a reliable history is forthcoming or whether a family member should be interviewed instead.
Specific questions clarify the quality, intensity, distribution, duration, and frequency of each symptom. What aggravates and attenuates the symptom and whether past treatment was effective should be determined. Asking the patient to describe the order in which symptoms occur can help identify the cause. Specific disabilities should be described quantitatively (eg, walks at most 25 ft before stopping to rest), and their effect on the patient’s daily routine noted. Past medical history and a complete review of systems are essential because neurologic complications are common in other disorders, especially alcoholism, diabetes, cancer, vascular disorders, and HIV infection. Family history is important because migraine and many metabolic, muscle, nerve, and neurodegenerative disorders are inherited. Social, occupational, and travel history provides information about unusual infections and exposure to toxins and parasites.
Sometimes neurologic symptoms and signs are functional or hysterical, reflecting a psychiatric disorder. Typically, such symptoms and signs do not conform to the rules of anatomy and physiology, and the patient is often depressed or unusually frightened. However, functional and physical disorders sometimes coexist, and distinguishing them can be challenging.
The neurologic examination begins with careful observation of the patient entering the examination area and continues during history taking. The patient should not be helped, so that difficulties in function can become apparent. The patient’s speed, symmetry, and coordination while moving to the examining table are noted, as are posture and gait. The patient’s demeanor, dress, and responses provide information about mood and social adaptation. Abnormalities in language, speech, or praxis; neglect of space; unusual posturing; and other disorders of movement may be apparent before formal testing.
As information is obtained, a skilled examiner may include certain components of the examination and exclude others based on a preliminary hypothesis about the anatomy and pathophysiology of the problem. If the examiner is less skilled, complete neurologic screening is done.
(see also Approach to the Patient With Mental Symptoms.) The patient’s attention span is assessed first; an inattentive patient cannot cooperate fully and hinders testing. Any hint of cognitive decline requires examination of mental status (see Examination of Mental Status), which involves testing multiple aspects of cognitive function (eg, orientation to time, place, and person; attention and concentration; memory; verbal and mathematical abilities; judgment; reasoning). Loss of orientation to person (ie, not knowing one’s own name) occurs only when obtundation, delirium, or dementia is severe; when it occurs as an isolated symptom, it suggests malingering. Insight into illness and fund of knowledge in relation to educational level are assessed, as are affect and mood (see page Mood Disorders).
The patient is asked to follow a complex command that involves 3 body parts and discriminates between right and left (eg, “Put your right thumb in your left ear, and stick out your tongue”). The patient is asked to name simple objects and body parts and to read, write, and repeat simple phrases; if deficits are noted, other tests of aphasia are needed (see page Diagnosis). Spatial perception can be assessed by asking the patient to imitate simple and complex finger constructions and to draw a clock, cube, house, or interlocking pentagons; the effort expended is often as informative as the final product. This test may identify impersistence, perseveration, micrographia, and hemispatial neglect. Praxis (cognitive ability to do complex motor movements) can be assessed by asking the patient to use a toothbrush or comb, light a match, or snap the fingers.
(see also Neuro-ophthalmologic and Cranial Nerve Disorders.) Smell, a function of the 1st (olfactory) cranial nerve, is usually evaluated only after head trauma or when lesions of the anterior fossa (eg, meningioma) are suspected or patients report abnormal smell or taste. The patient is asked to identify odors (eg, soap, coffee, cloves) presented to each nostril. Alcohol, ammonia, and other irritants, which test the nociceptive receptors of the 5th (trigeminal) cranial nerve, are used only when malingering is suspected.
The 2nd (optic), 3rd (oculomotor), 4th (trochlear), and 6th (abducens) cranial nerves involve the visual system.
For the 2nd cranial nerve , visual acuity is tested using a Snellen chart for distance vision and a handheld chart for near vision; each eye is assessed individually, with the other eye covered. Color perception is tested using standard pseudoisochromatic Ishihara or Hardy-Rand-Ritter plates that have numbers or figures embedded in a field of specifically colored dots. Visual fields are tested by directed confrontation in all 4 visual quadrants. Direct and consensual pupillary responses are tested (see also Diagnosis). Funduscopic examination is also done.
For the 3rd, 4th, and 6th cranial nerves , eyes are observed for symmetry of movement, globe position, asymmetry or droop of the eyelids (ptosis), and twitches or flutters of globes or lids. Extraocular movements controlled by these nerves are tested by asking the patient to follow a moving target (eg, examiner’s finger, penlight) to all 4 quadrants (including across the midline); this test can detect nystagmus and palsies of ocular muscles. Anisocoria or differences in pupillary size should be noted in a dimly lit room. The pupillary light response is tested for symmetry and briskness.
For the 5th (trigeminal) nerve , the 3 sensory divisions (ophthalmic, maxillary, mandibular) are evaluated by using a pinprick to test facial sensation and by brushing a wisp of cotton against the lower or lateral cornea to evaluate the corneal reflex. If facial sensation is lost, the angle of the jaw should be examined; sparing of this area (innervated by spinal root C2) suggests a trigeminal deficit. A weak blink due to facial weakness (eg, 7th cranial nerve paralysis) should be distinguished from depressed or absent corneal sensation, which is common in contact lens wearers. A patient with facial weakness feels the cotton wisp normally on both sides, even though blink is decreased. Trigeminal motor function is tested by palpating the masseter muscles while the patient clenches the teeth and by asking the patient to open the mouth against resistance. If a pterygoid muscle is weak, the jaw deviates to that side when the mouth is opened.
The 7th (facial) cranial nerve is evaluated by checking for hemifacial weakness. Asymmetry of facial movements is often more obvious during spontaneous conversation, especially when the patient smiles or, if obtunded, grimaces at a noxious stimulus; on the weakened side, the nasolabial fold is depressed and the palpebral fissure is widened. If the patient has only lower facial weakness (ie, furrowing of the forehead and eye closure are preserved), etiology of 7th nerve weakness is central rather than peripheral. Taste in the anterior two thirds of the tongue can be tested with sweet, sour, salty, and bitter solutions applied with a cotton swab first on one side of the tongue, then on the other. Hyperacusis may be detected with a vibrating tuning fork held next to the ear.
Because the 8th (vestibulocochlear, acoustic, auditory) cranial nerve carries auditory and vestibular input, evaluation involves testing hearing (see page Evaluation of Hearing Loss : Evaluation) and balance.
The 9th (glossopharyngeal) and 10th (vagus) cranial nerves are usually evaluated together. Whether the palate elevates symmetrically is noted. A tongue blade is used to touch one side of the posterior pharynx, then the other, and symmetry of the gag reflex is observed; bilateral absence of the gag reflex is common among healthy people and may not be significant. In an unresponsive, intubated patient, suctioning the endotracheal tube normally triggers coughing. If hoarseness is noted, the vocal cords are inspected. Isolated hoarseness (with normal gag and palatal elevation) should prompt a search for lesions (eg, mediastinal lymphoma, aortic aneurysm) compressing the recurrent laryngeal nerve.
The 11th (spinal accessory) cranial nerve is evaluated by testing the muscles it supplies. For the sternocleidomastoid, the patient is asked to turn the head against resistance supplied by the examiner’s hand while the examiner palpates the active muscle (opposite the turned head). For the upper trapezius, the patient is asked to elevate the shoulders against resistance supplied by the examiner.
The 12th (hypoglossal) cranial nerve is evaluated by asking the patient to extend the tongue and inspecting it for atrophy, fasciculations, and weakness (deviation is toward the side of a lesion).
The limbs and shoulder girdle should be fully exposed, then inspected for atrophy, hypertrophy, asymmetric development, fasciculations, myotonia, tremor, and other involuntary movements, including chorea (brief, jerky movements), athetosis (continuous, writhing movements), and myoclonus (shocklike contractions of a muscle). Passive flexion and extension of the limbs in a relaxed patient provide information about muscle tone. Decreased muscle bulk indicates atrophy, but bilateral atrophy or atrophy in large or concealed muscles, unless advanced, may not be obvious. In the elderly, loss of some muscle mass is common. Hypertrophy occurs when one muscle must work harder to compensate for weakness in another; pseudohypertrophy occurs when muscle tissue is replaced by excessive connective tissue or nonfunctional material (eg, amyloid).
Fasciculations (brief, fine, irregular twitches of the muscle visible under the skin) are relatively common. Although they can occur in normal muscle, particularly in calf muscles of the elderly, fasciculations usually indicate lesions of the lower motor neuron (eg, nerve degeneration or injury and regeneration). Myotonia (slowed relaxation of muscle after a sustained contraction or direct percussion of the muscle) indicates myotonic dystrophy and may be demonstrated by inability to quickly open a clenched hand. Increased resistance followed by relaxation (clasp-knife phenomenon) and spasticity indicates upper motor neuron lesions. Lead-pipe rigidity (uniform rigidity throughout the range of motion), often with cogwheeling, suggests a basal ganglia disorder.
Patients who report weakness may mean fatigue, clumsiness, or true muscle weakness. Thus, the examiner must define the precise character of symptoms, including exact location, time of occurrence, precipitating and ameliorating factors, and associated symptoms and signs (see page Weakness). Limbs are inspected for weakness (when extended, a weak limb drifts downward), tremor, and other involuntary movements. The strength of specific muscle groups is tested against resistance, and one side of the body is compared with the other. However, pain may preclude a full effort during strength testing. With hysterical weakness, resistance to movement may be initially normal, followed by a sudden giving way.
Subtle weakness may be indicated by decreased arm swing while walking, pronator drift in an outstretched arm, decreased spontaneous use of a limb, an externally rotated leg, slowing of rapid alternating movements, or impairment of fine dexterity (eg, ability to fasten a button, open a safety pin, or remove a match from its box). Subtle motor weakness can often be detected by Tiller and mini-Tiller testing. With each hand, the patient makes a fist (in the Tiller test) or a fist with the index finger extended (in the mini-Tiller test) and then rotates the 2 around each other. The weaker limb becomes fixed in space while the stronger revolves around it.
Strength should be graded. The following scale, originally developed by The Medical Research Council of the United Kingdom, is now used universally:
The difficulty with this and similar scales is the large range in strength possible between grades 4 and 5. Distal strength can be semiquantitatively measured with a handgrip ergometer or with an inflated BP cuff squeezed by the patient.
Functional testing often provides a better picture of the relationship between strength and disability. As the patient does various maneuvers, deficiencies are noted and quantified as much as possible (eg, number of squats done or steps climbed). Rising from a squatting position or stepping onto a chair tests proximal leg strength; walking on the heels and on tiptoe tests distal strength. Pushing with the arms to get out of a chair indicates quadriceps weakness. Swinging the body to move the arms indicates shoulder girdle weakness. Rising from the supine position by turning prone, kneeling, and using the hands to climb up the thighs and slowly push erect (Gowers sign) suggests pelvic girdle weakness.
Normal gait, stance, and coordination require integrity of the motor, vestibular, and proprioceptive pathways (see also Movement and Cerebellar Disorders). A lesion in any of the pathways causes characteristic deficits: Cerebellar ataxia requires a wide gait for stability; footdrop causes a steppage gait (lifting the leg higher than normal to avoid catching the foot on surface irregularities); pelvic muscle weakness causes waddling; and spastic leg causes scissoring and circumduction. Patients with impaired proprioception must constantly observe placement of their feet to avoid tripping or falling. Coordination can be tested with finger-to-nose or knee-to-shin maneuvers, which help detect ataxic movements.
The best screening test for sensory loss uses a safety pin to lightly prick the face, torso, and 4 limbs; the patient is asked whether the pinprick feels the same on both sides and whether the sensation is dull or sharp. The pin is discarded after use to avoid potential transmission of bloodborne disorders (eg, HIV infection, hepatitis).
Cortical sensory function is evaluated by asking the patient to identify a familiar object (eg, coin, key) placed in the palm of the hand (stereognosis) and numbers written on the palm (graphesthesia) and to distinguish between 1 and 2 simultaneous, closely placed pinpricks on the fingertips (2-point discrimination).
Temperature sense can be tested with a cold tuning fork that has one prong rubbed warm by the examiner’s palm or with test tubes containing warm and cold water.
Joint position sense is tested by moving the terminal phalanges of the patient’s fingers, then the toes, up or down a few degrees. If the patient cannot identify these tiny movements with eyes closed, larger up-and-down movements are tried before testing the next most proximal joints (eg, testing the ankles if toe movement is not perceived). Pseudoathetosis refers to involuntary writhing, snakelike movements of a limb that result from severe loss of position sense; motor pathways, including those of the basal ganglia, are preserved. The brain cannot sense where the limb is in space so the limb moves on its own, and the patient must use vision to control the limb’s movements. Typically, when the eyes are closed, the patient cannot locate the limb in space. Inability to stand with feet together and eyes closed (Romberg test) indicates impaired position sense in the lower extremities. When cerebellar disease is present, the patient stands with the feet apart but as close together as possible without falling and only then closes the eyes. Rarely, a positive result is due to severe bilateral loss of vestibular function (eg, aminoglycoside toxicity).
To test vibration sense, the examiner places a finger under the patient’s distal interphalangeal joint and presses a lightly tapped 128-cycle tuning fork on top of the joint. The patient should note the end of vibration about the same time as the examiner, who feels it through the patient’s joint.
A cotton wisp can be used to test light touch.
Stocking-glove distribution: Distal peripheral nerves
Single dermatomal or nerve branch distribution: Isolated nerves (mononeuritis multiplex) or nerve roots (radiculopathy)
Sensation reduced below a certain dermatomal level: Spinal cord
Saddle area sensory loss: Cauda equina
Crossed face-body pattern: Brain stem
Hemisensory loss: Brain
Midline hemisensory loss: Thalamus or functional (psychiatric)
Location of the lesion is confirmed by determining whether motor weakness and reflex changes follow a similar pattern. Patchy sensory, motor, and reflex deficits in a limb suggest lesions of the brachial or pelvic plexus.
Deep tendon (muscle stretch) reflex testing evaluates afferent nerves, synaptic connections within the spinal cord, motor nerves, and descending motor pathways. Lower motor neuron lesions (eg, affecting the anterior horn cell, spinal root, or peripheral nerve) depress reflexes; upper motor neuron lesions (ie, non–basal ganglia disorders anywhere above the anterior horn cell) increase reflexes (see page Amyotrophic Lateral Sclerosis and Other Motor Neuron Diseases).
Reflexes tested include the biceps (innervated by C5 and C6), radial brachialis (by C6), triceps (by C7), quadriceps knee jerk (by L4), and ankle jerk (by S1). Any asymmetric increase or depression is noted. Jendrassik maneuver can be used to augment hypoactive reflexes: The patient locks the hands together and pulls vigorously apart as a tendon in the lower extremity is tapped. Alternatively, the patient can push the knees together against each other, while the upper limb tendon is tested.
Lightly stroking the 4 quadrants of the abdomen should elicit a superficial abdominal reflex. Depression of this reflex may be due to a central lesion, obesity, or lax skeletal muscles (eg, after pregnancy); its absence may indicate spinal cord injury.
Pathologic reflexes (eg, Babinski, Chaddock, Oppenheim, snout, root, grasp) are reversions to primitive responses and indicate loss of cortical inhibition.
Babinski, Chaddock, and Oppenheim reflexes all evaluate the plantar response. The normal reflex response is flexion of the great toe. An abnormal response is slower and consists of extension of the great toe with fanning of the other toes and often knee and hip flexion. This reaction is of spinal reflex origin and indicates spinal disinhibition due to an upper motor neuron lesion. For Babinski reflex, the lateral sole of the foot is firmly stroked from the heel to the ball of the foot with a tongue blade or end of a reflex hammer. The stimulus must be noxious but not injurious; stroking should not veer too medially, or it may inadvertently induce a primitive grasp reflex. In sensitive patients, the reflex response may be masked by quick voluntary withdrawal of the foot, which is not a problem in Chaddock or Oppenheim reflex testing. For Chaddock reflex, the lateral foot, from lateral malleolus to small toe, is stroked with a blunt instrument. For the Oppenheim reflex, the anterior tibia, from just below the patella to the foot, is firmly stroked with a knuckle.
The snout reflex is present if tapping a tongue blade across the lips causes pursing of the lips.
The rooting reflex is present if stroking the lateral upper lip causes movement of the mouth toward the stimulus.
The grasp reflex is present if gently stroking the palm of the patient’s hand causes the fingers to flex and grasp the examiner’s finger.
The palmomental reflex is present if stroking the palm of the hand causes contraction of the ipsilateral mentalis muscle of the lower lip.
Hoffmann sign is present if flicking the nail on the 3rd or 4th finger elicits involuntary flexion of the distal phalanx of the thumb and index finger.
For the glabellar sign , the forehead is tapped to induce blinking; normally, each of the first 5 taps induces a single blink, then the reflex fatigues. Blinking persists in patients with diffuse cerebral dysfunction.
Testing for clonus (rhythmic, rapid alternation of muscle contraction and relaxation caused by sudden, passive tendon stretching) is done by rapid dorsiflexion of the foot at the ankle. Sustained clonus indicates an upper motor neuron disorder.
Sphincteric reflexes may be tested during the rectal examination. To test sphincteric tone (S2 to S4 nerve root levels), the examiner inserts a gloved finger into the rectum and asks the patient to squeeze it. Alternatively, the perianal region is touched lightly with a cotton wisp; the normal response is contraction of the external anal sphincter (anal wink reflex). Rectal tone typically becomes lax in patients with acute spinal cord injury or cauda equine syndrome.
For the bulbospongiosus reflex , which tests S2 to S4 levels, the dorsum of the penis is tapped; normal response is contraction of the bulbospongiosus muscle.
For the cremasteric reflex , which tests the L2 level, the medial thigh 7.6 cm (3 in) below the inguinal crease is stroked upward; normal response is elevation of the ipsilateral testis.
(See also Autonomic Nervous System.) Assessment involves checking for postural hypotension, heart rate changes in response to the Valsalva maneuver, decreased or absent sweating, and evidence of Horner syndrome (unilateral ptosis, pupillary constriction, facial anhidrosis). Disturbances of bowel, bladder, sexual, and hypothalamic function should be noted.
In a patient presenting with acute stroke, radial pulse and BP in the 2 arms are compared to check for painless aortic dissection, which can occlude a carotid artery and cause stroke. The skin, sclerae, fundi, oral mucosae, and nail beds are inspected for hemorrhages and evidence of cholesterol or septic emboli; auscultation over the heart can detect new or evolving murmurs and arrhythmias. Bruits over the cranium may indicate an arteriovenous malformation or fistula or, occasionally, redirected blood flow across the circle of Willis after carotid occlusion. Auscultation over the carotid arteries can detect bruits near the bifurcation; vigorous palpation should be avoided. By running the bell of the stethoscope down the neck toward the heart, the examiner may identify a change in character that can distinguish a bruit from a systolic heart murmur. Decreased vigor of the carotid upstroke suggests a stenotic lesion.
Peripheral pulses are palpated to check for peripheral vascular disease. The temporal arteries are palpated; enlargement or tenderness may suggest temporal arteritis.
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